The Pettyjohn IRON3 is an analog overdrive pedal from Pettyjohn Electronics, aimed squarely at what the maker calls "that thick, smooth, cranked American amp sound." It is a soft clipping circuit built around a modified JRD4558 chip, with a US made, studio grade iron core transformer that can be switched out from the rear of the pedal. It is the current version of the IRON circuit, which Pettyjohn first issued inside the PettyDrive and later refined in the IRON V3.1
What it does to your sound
Pettyjohn positions the IRON3 as a continuation of the IRON voice: "The IRON3 is all about that thick, smooth, cranked American amp sound and picks up where the IRON V3 left off."1 The IRON V3 page describes the same family trait as a cranked, thick American amp sound with depth, warmth, character and dimensional feel from real magnetic saturation, which is where the iron core transformer comes in.2 The transformer is bypassable via a rear push button switch, so the magnetic saturation stage can be taken out of the path entirely.1
The clipping character is set by a toggle with a SYM position. Pettyjohn describes it as activating a symmetrical silicon diode clipping array, now based on the famous Blues Breaker symmetrical array, with 2x the headroom of the Tube Screamer style arrangement and upgraded NOS diodes. For context on that Tube Screamer lineage, see the Boss SD-1 vs Ibanez TS9 comparison.1
A LEVEL knob controls the output signal level.1 The company also markets the pedal's analog magnetics under the banner "Maximized Tone with the Power of Analog Magnetics!"1
Power and practicalities
The IRON3 runs 36 volts internally, converted from a standard 9V adapter, and draws 250mA (Standard) or 300mA (Deluxe). That is well beyond what a daisy chain output typically delivers, so plan a dedicated supply output for it.1
Other practical details from the maker:
- Handmade in the Pacific Northwest, USA, as part of the Pettyjohn3 "Cubed" Series1
- Hand-finished hardwood Cherry top, with other custom shop options available1
- True Bypass Footswitch with Pro Grade Switch1
From the PettyDrive V1 to the IRON3
The IRON circuit has a long lineage inside Pettyjohn's range. The company describes the IRON3 as "optimizing our IRON circuit originally issued in the PettyDrive V1," the dual-channel pedal that started much of the line.1 The IRON V3 that preceded it was itself a PCB redesign, done to update the features and include an optional studio grade, USA made iron core transformer.2
The first standalone IRON, the IRON V1, was described by Pettyjohn in 2018 as a low to medium gain overdrive with a classic American character: "A rich bluesy 'Blackface'. A tweedy heart of gold. A classic 'American' tone machine through and through." That unit also shipped with an extra JRC4558 chip inside so players could swap it for more tone possibilities.3
The IRON3 continues a lineage: Pettyjohn states it picks up where the IRON V3 left off, optimizing the IRON circuit originally issued in the PettyDrive V1. The IRON V3 itself had a redesigned PCB to update features and include an optional studio-grade, USA made iron core transformer.1
Availability
Pettyjohn states the IRON3 is now in standard shipping, with an estimated build time to shipping of 5 to 15 business days, and lists it from $399.00 as a sale price. The previous IRON V3 page showed limited stock of one left, so the IRON3 is the version currently being built.12
Questions
Is the Pettyjohn IRON3 true bypass?
Yes. Pettyjohn specifies a True Bypass Footswitch with a Pro Grade Switch on the IRON3. The pedal also has a second bypass function: the iron core transformer on the rear of the unit can be switched out with a push button, so you can run the pedal with or without the transformer in the signal path while the footswitch handles true bypass switching.
Can you turn off the transformer on the IRON3?
Yes. The IRON3 carries a US made, studio grade iron core transformer that is bypassable via a rear push button switch. That means the magnetic saturation stage can be taken out of the circuit when you want the plainer overdrive voice, and switched back in when you want the depth and warmth the transformer contributes.
What op-amp chip does the IRON3 use?
The IRON3 is built around the classic JRD4558 chip, modified by Pettyjohn. The company describes the circuit as a simple soft clipping design based on that chip. The 4558 family of chips has a long history in overdrive pedals, and Pettyjohn's earlier IRON V1 even shipped with an extra JRC4558 chip inside the unit so players could swap it out for more tone possibilities.
What is the difference between the IRON3 and the IRON V3?
The IRON3 picks up where the IRON V3 left off, optimizing the same IRON circuit that was originally issued in the PettyDrive V1. The IRON V3 itself was a redesign of the PCB to update features and add an optional studio grade, USA made iron core transformer. The IRON3 is the current version, handmade in the Pacific Northwest with a hand-finished hardwood Cherry top, while the IRON V3 page showed limited stock of one left.
How much current does the Pettyjohn IRON3 draw?
Pettyjohn lists 250mA for the Standard version and 300mA for the Deluxe version, both from a standard 9V adapter. The pedal converts that to 36 volts of internal power. That current draw is high for a single pedal, so it needs its own supply output rather than a shared daisy chain.
Sources (3)
- IRON3 | Pettyjohn Elec, Pettyjohn Electronics
- IRON V3 | Pettyjohn Elec, Pettyjohn Electronics
- A Drive For All Occasions, Pettyjohn Electronics, 2018-12-13
